1. Field of the Disclosure
The present disclosure relates to a quantum dot infrared photodetector, for example, to a quantum dot infrared photodetector with a well in dot structure.
2. Description of the Related Art
Infrared photodetectors are widely used in military and astronomy applications. In recent years, t research has been devoted to the development of quantum dot infrared photodetectors (QDIP), because QDIPs exhibit better performance characteristics than traditional quantum well infrared photodetectors (QWIP). For example, QDIPs have an intrinsic sensitivity to the normal incident light, whereas QWIPs cannot absorb normal incident light, are able to operate in higher temperatures, and have a longer lifetime, etc.
Operability at high temperatures is important for infrared photodetectors to cut cooling system costs and expand their applicability. Due to the rapid increase of dark current, which is proportional to
      exp          -              1        kT              ,QDIPs are often difficult to operate at high temperatures (>200 K or approximate to room temperature). In order to achieve high-temperature operation, various methods have been applied to try to reduce the dark current. For example, a AlGaAs blocking layer, a tunneling barrier QDIP (T-QDIP), or a confinement enhancing layer formed on the quantum dot layer may be used to reduce the dark current and enhance the operation temperature of QDIPs. However, a complicated and precise epitaxial process is needed to obtain high responsivity and detectivity at high temperature.
More particularly, for standard undoped-InAs QDIPs, the photocurrent of QDIPs results from carries in the QDs supplied from the n+ top and bottom contacts and then swipes by the bias voltage. However, the efficiency of the carrier injection into the QD layer further away from the contacts is low.
Because of the above-mentioned reasons, the development of QDIPs infrared photodetectors that are operable to avoid severe dark current and enhance the photocurrent are desired.